1. Technical Field
The present invention relates to a piezoelectric mechanism for gas lighters which includes a number of advantages compared to those currently used in the art.
2. Background Art
As is known, all piezoelectric mechanisms are basically formed by a pair of telescopic assemblies that are mutually aided by a spring which maintains them in a position of maximum extension. Such mechanisms include means that limit the movement of the assemblies to prevent accidental separation. Solidly fixed to one of these assemblies, indistinctly, is a crystal or piezoelectric element which provides a lighting spark when impacted by a plexor. The piezoelectric element, in turn, is placed between a metallic piece, called an "anvil", and another piece which actually receives the impact of the plexor, called a "base" or "limiting piece".
The plexor functions in the axial void of the internal telescopic body and, in a rest position, is distant from the piezoelectric element due to the presence of a retaining mechanism. When a manual compressive force is applied over the telescopic set, ignition is produced by reducing the action of the spring which acts on the telescopic set, while simultaneously compressing a second spring that afterwards impulses the plexor in the moment of triggering, thus creating the impact energy of the plexor against the base to generate the spark. The plexor is guided by a pair of facing longitudinal slots which crosses the wall of one of the tubular assemblies, each one of them carrying the dimetient lugs of the plexor.
The plexor is retained at rest by its transversal lugs, each one of which is positioned in open lugs at one side of the longitudinal slot with respect to said tubular assembly. These lugs are introduced into the open lugs when the plexor is rotated. For the plexor to make a small rotation, both lugs must leave the retaining notches and re-enter them after impact so that the repositioning of the mechanism takes place. At the end of the compression run of the telescopic set and during its distension, respectively, the dimetient lugs of the plexor are pressed by the edges in ramp of windows each one provided in the other telescopic body, where these lugs also function.
Currently, although the external shape of the telescopic set is quadrangular and the entire mechanism is located in a housing prepared for such a purpose in the lighter assembly, both components must not have relative rotation. In some cases, this problem is resolved by making the internal section of the external assembly and the external shape of the internal assembly different, thus enabling the introduction of a plexor carrying dimetient lugs. These lugs are placed in a rotated position, in the existing windows in the other telescopic assembly. However, this asymmetrical form of the set is difficult to mold.
In other cases, these sections are made circular. This implies that the dimetient lugs of the plexor are materialized by a gudgeon that has to be assembled after the introduction of the plexor and simultaneously to the compression performed on the telescopic set. The assembly of this gudgeon considerably increases production costs of the piece and those of assembly of the mechanism.
Spanish patent P-8902741 discloses a piezoelectric mechanism for gas lighters in which the aforementioned problems referred to were resolved, or at least were favorably reduced, both in the economic aspect and in the functional and structural ones. In this patent, it is possible to do without the angular displacement relative to both telescopic components, by anticipating in the external assembly a pair of lugs that perform with the function of a linch pin. These lugs operate in the interior of the same slots provided in the internal telescopic assembly for axial displacement of the plexor, such that these slots need to have a greater length than is necessary only for the guidance of the plexor. Shortening of the run is obtained for the electric current, since it only circulates through the anvil, piezoelectric element, the plexor limiting piece and the external telescopic assembly. This is different than other previous mechanisms in which the electric current also passes through the springs that aid the plexor and the telescopic set. This run is short and the electric current used to generate the spark passes from the plexor limiting piece or the lower seating of the piezoelectric element to the external telescopic assembly linch pins. There exists a small play in the contact surfaces of these elements that can cause failures in ignition or can result in current derivations through another run somewhat longer. This is especially true when the seating of the plexor on the limiting piece and the seating of the limiting piece on the internal face of the piezoelectric element is not in perfect alignment.
In all cases, the spring aiding the plexor is partially or totally guided within the interior of the telescopic assembly that houses the plexor. Establishing support in its other extreme is a cap that is fixed to the free end of the assembly. This cap is provided with lugs with saw-tooth sections, which are introduced in respective lateral windows in facing walls of the telescopic assembly and are being immobilized in this fixed position.
It has been found that all prior piezoelectric mechanisms, that is, those having a telescopic set with its adjacent elements, have slight gaps in its housing in the lighter assembly, mainly in an axial sense, which provokes an undesired movement of the pulser.
In addition, the gap or internal base of the telescopic set is directly rested on a stud that emerges from the bottom of the assembly housing, a known way this presents its extreme top in a conical form, which is then introduced into a small hole or impression which is provided as a seating to contribute to the lateral immobilization of the piezoelectric mechanism, and to endow to the set a certain rigidity which determines the accumulation of gaps. Thus, a small movement of the piezoelectric mechanism is noted on pulsing, and even this does not recover to its position of rest efficiently. In trying to solve this problem, an additional spring is mounted, placed between the bottom of the housing for the piezoelectric element and the lower cap of the latter. This complicates the device and makes it more expensive to manufacture. The spring is necessary, however, to open and recover gas during the rocking of the forked ring during functioning of the gas burner of the lighter.